JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="block">Hello!</div>
</div>
<br/><br/>
<button id="go">&raquo; Run</button>

CSS

#container{width:300px; background-color:pink; float:left; height:80px;}
#block{width:100px; background-color:yellow; height:80px; float:left;}

JavaScript

$("#go").click(function(){
  $("#block").animate({
    width: "70%"
  }, 800 );
});